The invention relates to a rotating cutting tool, particularly a boring bar with the features of the preamble of claim 1 as well as a process for machining with the assistance of such a cutting tool a number of bores that are particularly spaced apart from one another by a predetermined spacing in the axial direction.
A boring bar of this type as well as a process of this type can be found in EP 0 771 602 B1.
Bearing shafts, for example camshafts or crankshafts in motor vehicles, are typically supported at multiple bearing bars spaced apart from one another axially in bearing bores, which are designated hereinafter simply as bores. Individual bores in this case are typically bored out to a final dimension with the assistance of a so-called line boring bar. To this end, the boring bar has cutting edges, each of which is provided for machining a respective bore, arranged offset with respect to one another by the respective spacing in the axial direction. Thus, several of the bores are machined simultaneously by the cutting edges spaced apart from one another in the axial direction.
Therefore, working positions are formed at the boring bar, with one cutting edge each according to the spacing of the bores. Typically, only one cutting edge is formed per working position to do this.
The boring bar must be guided or supported for the boring process. Direct support of the boring bar in the area of the respective cutting edges is not readily possible via guide elements such as guide rails, as known, for example, with reamers, because the boring bar must initially be inserted through the rough bores to be processed.
In order to make this possible, cutting edges and/or guide elements are arranged offset in the radial direction in accordance with EP 0 771 602 B1. The initially radially offset elements are extended in the radial direction after the retraction of the boring bar, which means that a respective bore can be bored out to the desired final dimension. This design requires a moving, mechanically complex arrangement of the cutting edges and/or guide elements. In addition, there must be reliable assurance that when the boring bar is withdrawn, the elements are radially retracted, at least a section, so that the surface of the machined bearing bores is not damaged when the boring bar is removed.